Rail flaw detector



Aug. 9, 1932. H. c. DRAKE RAIL FLAW DETECTOR Filed April kll. 2 SheetSI-Sheet l J im?.

TliilLlll H. C. DRAKE RAIL FLAW DETECTOR Aug. 9, 1932.

2 Sheets-Sheet 2 l y INVENTORY /Yarcoaf G; ra n BY Filed April 11, 1.92?-

30 car embodying my invention.

, amplification unit.

d UOURT C.

si 0F HEHPSTED, NEW YORK, SSIGNOB,BY MESNE ASSIGNMENTS,

TO SPERBY PRODUCTS, INC., F BROOKLYN, NEW .YORK A CORPORATION OF NEW YORK BAIL ELAW DETECTOR Application filed April 11, 1927. Serial No. 182,981.

'. way rails after they are laid in the track. It

is now well recognized that such flaws develop in rails after they have been in use for some time, but so far as I am aware no successful method has been developed prior to my in- U vention for detecting such flaws in laid track until the rail actually breaks, which,` of

course, on main line track, results in a derailment and many times in a serious wreck.

The purpose of my invention is to devise a mobile testing unit for rails which may be moved al0ng\the track and-which will indi.- cate the presence of a flaw as the unit passes over the same. This indication may be in the form of 'a record on achart or other audible or Visiblel indication and ifdesired the def ective rail itself may be marked automatically. It will also be obvious from the following description that my invention is equally .adapted'to testing rails or any metallic bars or plates at the rollin mill or Shop as well as after the track has en laid.

Referring to the drawings in which several preferred forms of my invention are shown,

. Fig.- 1 is a diagrammatic plan view of a test Fig. 2 is a side elevation of thelsame. Fig. 3 .is a wiring` diagram showing one l Fig. 4 is a diagram showing the character ofthe markings on the chart. f.

Fig. 5 is a plan view of the recording pen mechanism. i

Fig. 6 is an elevation of the same. Fig. .7 is a sectional'detail of a means for marking a defective rail.

Fig. 8 is an additional wiring diagram showing the rail marking means and also an audible signal which may be actuated when a aw is passed over.

Fig. 9 is an enlarged side elevation of a modied form of contact for the relay.

Fig. 10 is a plan view of the same. Fig. 11 is a wiring diagram of a modified form of amplification system employing a transformer coupled type of radib ampli er.

For detecting hidden aws, I prefer to make use of the fact that the presence f the iiaw increases the resistance of the head of the rail in the immediate vicinity of the aw sothat by passing a heavy current through the rail, employing suitable potentiometer `contacts and a` novel amplifying arrangement, the presence thereof may be detected. Current is. shown as supplied to each rail R and R through a series of heav brushes 1, 2, 3 and 4 to which is connecte a heavy current, low voltage generator 5 which may be drivenv by combustion Vor other engine 6 on the test car. vA separate generator 5 is shown for the other rail R. of both generators ma be excited by a separate exciter. Preferably the generator 5 is connected to the two inside brushes 2 and 3,

and the two outside brushes 1 and '4 are cross- The fields 70 connected by a heavy copper bar 7 of low resistance. If the current then enters through brush 2 it will: divide, half ofthe same owing through the rail to brush 3, and

.the other half iowing in the opposite direcjtion through the rail to brush 1, thence through copper conductor 7 to brush 4 and thence back to brush 3, the spacing between brushes 2 and 3 being equal to the combined distance between brushes 1 and 2 and brushes 3 and 4. By this means and by insulatingy the wheels on one side of the car from those on the other, as by insulating bushings B between the wheels 21 and the axle 20, leakage of current into the block signal system of the railroad and o ration of the signals by the car is preven since the two outside brushes 1 and 4 prevent any current from leaking beyond the car. Besides, this enables'one to tapy the rail at three points, i. e., between o em loyment of only one generator.

` bers of each pair of contacts. These contacts- `rail as do the brushes.

etween veach pair of brushes as aforesaid I place a pair of exploring or potentiometer contacts 8, 9 and 10 for very accurately detecting any variation in voltage drop 1n the small sections of the rail between the memmay be in the form of small copper brushes 73 and 74 or small wheels 75 and 76 as shown in Figs. 9 and 10. Saidwheels are shown as mounted on pivoted arms 77, 77 pressed against the rail by springs 78. The small wheels or trolleys have the advanta e over the sliding brushes that they do not ecome heated at their points of contact with the Such heating should be avoided in a sensitive thermionic system of this kind since it may generate thermocouples in the system which would disturb the accuracy of the'indicator. Current 1s lead to the wheels by brushes 79. The entire set of brushes both large and small may be mounted on a common frame 10 which may be raised and lowered by any suitable means such as a crank handle 11 mounted on a shaft 12 which has worms 13 and 14 thereon geared to worin wheels 15. .Said wheels are each provided with an arm 16 engaging arallel linka e 17 of frame 10 that the rushes may e raised and lowere crank 11. Preferably also the same crank serves to' raise and lower agpair of stiff, revolving brushes 18, 19 for cleaning the rail when the device is in operation, said brushesy being shown as revolved from the axle 20 of the car wheels 21 as by means of a pinion 22 and gear 23.

Fig. 3 represents a preferred means for ampllfying the variation in voltage drop between the members of the pairs of contants 8 when a flaw is passed over. Said contacts are placed in electrical relation with a cascade amplifying system 24 of the thermionic direct current type in which the contacts are placed so as to charge the grid 25 of No. 1 tube 26 with a (say) negative potential, the variations in the otential of the grid of this tube relative to t e filament 27 governing the other tubes of the amplifying system. The more negative the grid potential becomes with respect to the filament, the lower the output of the amplifier. y

If, howevcr,no further means is employed, the output of the system will increase to a very large figure if the contact between the brushes 8 and the rail becomes poor, or in case the brushes 8 bounce oli the rail, thereby reducing the negative potential to zero. To correct this difficulty a resistance 28, on *the order of 100,000 ohms or more, is inserted across the brushes 8 and a variable potentiometer 29 is provided which may be adjusted to give a predetermined output for the difference in potential drop due to the by rotating the f potentiometer and that due to the rail between the brushes 8. If any llaw is encountered the loss of potential at the rail increases and, therefore, the dierence between the potential drop (E1) of the potentiometer and rail (E2) becomes .smaller so that the output increases to actuate the indicator, but if the brushes bounce from the rail or bad contact is encountered, the drop (E2 at the rail becomes or approaches zero an therefore, the total potential (E1- 2) increases and the output drops toward or to zero, resulting in no indication or at least an indication of a different character from that caused by a flaw.

Preferably also separate B batteries are rovided for some or all of the tubes. If, or instance, the same B battery 31 were used for the last tube 30 as for the others tion. With a separate B battery 31 and 32 for the other tubes, this trouble is avoided. Each unit of the amplifyin system is preferably shielded as by metailic coverings 80, such covering also extendin to the wires 'leading tothe brushes 8, 9 an 10, as indicat.

ed at 81 and to the batteries 31 and 31', so that outside electrical influences are carefully excluded.

The last tube is connected directly or indirectly to some form of indicating mechanism 33. As shown it is connected to a winding 34 on a marker mechanism which gives an indication on a traveling chart 35 when a flaw is encountered. The chart lis shown as continuously actuated from the car wheels as by means of bevel gearing 36 and a sprocket and chain 37. Each pen or marker mechanism is shown as comprising a U-shaped magnet 38 (Figs. 5 and 6), a magnetizing coil 39 which may have current continuously supplied thereto, and said coil 34 in circuit with or controlled by the 'amplifying system.

An armature in the .form of a spring plate 41 pinned at its base projects through said last-named coil and up between the ends of said U-shaped magnet,-the armature being preferably of soft iron and having a pin 42 engaging a slot 43 in the reed 44 which holds the pen `45. Said pen is shown as dipping at one end 46 into an inkwell 47 and at the other end 48 as bearing on the chart 35. As the winding 34 is excited the soft iron armature becomes polarized andV is pulled towards one pole or the other of the permanent magnet as will be readily apparent, with a force proportional to the current flowing and against the spring bias of the plate 41,

Lerares tocause mark 51,-and if bad contact is encountered or the potentiometer brushes bounce from the rail, the pens will be pulled in the opposite direction to cause marks 90, 90 and 90 as the current through coil 34 will then decrease instead of increase.

The pen will also be actuated at each rail joint as shown at 53, 53 and 53, but the rail joints will actuate the pens to a much greater `positely in the two instances.

extent than the flaws and alsobe more sharply defined, so that their markings may-be readily distinguished from those caused by flaws on the chart. It will be understood that each set of brushes 8, 9 and 10 is connected to a separate amplifying system 24 and pen so that as shown there are three pens 45, and 45, for each rail, each pen tracing a separate line 50, and 50 on the chart and iving an indication 5,1, 51 ,and 51 of the aw as the connected pair of brushes pass over the same. This not only gives a triple check on the flaw but also furnishes an additional means for distinguishing between a flaw and a case where the entire brush system 1, 2, 3 and 4 bounces oi the rail, the case of noncontact with the rail, above considered, being where the detecting brushes 8, 9 or l0 loseI contact successively with the rail. The pens may be so arranged on the chart in staggered relation, as shown in Fig. 1, that for a flow or bad contact spot the markings '51, 51 and 51" or 9D, 90 and 90 on the chart appear in the same straight line across the same (Fig. 4). Where, however, the entire brush mechanism is bounced oi the rail, the markings of the pen will'be in staggered relation 52, 52 and 52, the three `pens marking simultaneously but the markings appearin in staggered relation as the brushes are p aced in staggered relation on the chart. The record C for rail R is shown on the left hand side of Fig. 4 and the record C' for the rail R .on the right hand side, the pens being shown as moved 0p- A aw appears at 151 on record C.

In addition to or instead of making a record of the iaws, I may provide'other signali ling means. In Fig. 8, for instance, I have shown both a means for giving an audible p signal when a iiaw is encountered and. also a means 'for marking a defectiverail at a point near the liaw. In this igure the pen mechanism is again shown at 33. An extra contact 55 is provided thereon which is so spaced as normally not tobeclosed by ordinary flaws,

but which is closed Aby the greater eiectl caused-by the rail joint. As the pen moves 4in the opposite direction, when contact isv lost or-poor, said contact and also contact 62 (hereinafterdescribed) are not closed under such conditions. When closed'said contact excites arelay coil 56 which controls an armature 57 having two sets of contacts 58 and 59. The uppercontact 58 is-cllosed by excitation Vof said coil 56 and is in circuit with a counter 60 or the like which counts the rail joints so that the defective rail may be located by counting the number of rails from a given point. Said contacts 58, however, are normally maintained open by a spring 60 and dashpot 61. The back contacts 59 are in circuit with another pair of contacts 62 which is controlled by the relay coil 34 ofthe second or third pair of brushes 9 or 10. This set of contacts when closed at the time thefirst set is closed will actuate the loud-speaker 63 and preferably also the rail-marking device- 64. From this it will be seen that for an ordinary iiaw the loud-speaker and marking-device will be operated because both the contacts 62 and 59 will be closed, since Contact 55 is not closed, by reason of the insui'licient movement of the pen. However, for -rail joints, since contact 55 is closed, the loudspeaker will not be operated as when contact 55 is closed the back'contacts at 59 will-be open, and the contacts 58 through the counter 60 be closed. For bad contact conditions, also, no operation will occur as-both contacts 55 and` 62 remain open. l

As shown, the rail-marking device is in the form of a paint-daubing device. Paint is placed in the container 66 to which is connected a source ofcompressed air through the pine 67. A valve 68 is placed in the outlet pipe 69 which is normally maintained closed but which isopened by means of an electromagnet or solenoid 7() connected to the slide valve 68, so that when the electro-magnet is excited, the valve will be momentarily opened and a splotch of paint splashed on the rail, the valve being closed again by spring 71.

Other forms of amplification may obvious- -v 'armature 92 normally biased to close back contacts 93 by means ofthe spring94. A coil 95 in circuit with switch 93 attracts the 'armature 92 to close contacts 96, which is in .the primary circuit. It will be understood that this contact device will vibrate rapidly to make and-break the primary circuit. In said circuit isplaced a transformer 97, the secondary being connected tothe grid 25 of the first tube 26. From this point on any number of stages maybe added as indicated by the transformer 97 vand ,tube 30, the last tube having its plate 98 in circuit with-the relay 33 as in the system described in connection with Fig. 3. It will be understood that -in such a system the C battery -99 is adjustlo' brushes are kept in contact with the rail during the test but may be raised when passing over switches, cross-overs, and the like. As each rail'joint is passed over three mark 53, 53 and 53 are made on the chart and if a '15 flaw is passed over three markings of a different character 51, 51', and 51" are made, y and at the same time the alarm 63 is sounded and a paint mark made on the rail. As ex- ,plained above, poor contact spots on the rail 2 orbouncing `of the brush system oi the rail,

make markings of a different character on the chart, and do not actuate the alarm or rail marker. Also I prefer to employ means in the amplifier circuit, such as condenser 98 shunt- 25" ed around resistance 99 to suppress oscillations of radio frequency so that only oscillations of much less frequency, such as occasioned by rail flawsz reach relay 33. i

In accordance withthe provisions of; the

3; patent statutes, I have herein described the principle and operation of my'invention, to-

f gether with the apparatus which Inow consider to represent the best embodiment thereof, but I desire to haveit understood that the. apparatus shown is only illustrativeandthat the invention can becarried out byf'fotherf means. Also, while it is designed to usethe various features and elements inthe combination and relations described` some of these- 40 may be altered and others omitted without interfering with the more generalresults outf lined, andthe invention-extends to such use.

-Havingdescribed my invention, what I claim and desire to secure by'Letters Patent 1s:

1. A rail Haw. detector comprising a plulrality of spaced contacts, means for moving I lrelatively said contact and rail, meansfor wfsupplying electric current to therail, a pair of contacts between said first-named contacts, means for detecting variations in the voltage drop therebetween, means Afor amplifying such variation, andrail-marking means actu- 55; ated therefrom to place` aumark. on the rail `adjacent each flaw. v A l 2. A rail flaw detector comprising a plurality of spaced contacts meansffo'r moving relatively said contact 'and rail, means for i' toi supplying .electriccuri'entjto the rail, a pair.

of contacts between said/:rst-nalned contaets,' ineans for detecting variations-in the voltage drop therebetween, meansfor amplis- V'ng-'such variatioman indicator operated 651 `erefrom, and' means for preventing operation of said indicator by rail joints, loss of proper rail contact andthe like.

3. In a rail flaw detector, a source of current, means movable along the rail for passing current through the rail between spaced points, detector means also movable with said first means and responsive to variations in the characteristics of current flow, railmarking means actuated therefrom to place a mark on the rail 'adjacent-each-ilaw, and means for preventing actuation of said railmarking means by rail joints.

4. A rail f law detector comprising a plurality of spaced contacts adapted to be moved along the rail, means for supplying electric current thereto, a pair of contacts between said first-named contacts, means for detecting variations in the voltage drop therebetween, means for amplifying such variation, railmarking means actuated therefrom-to place a mark on the rail adjacent each flaw, and means for preventing actuation of said marking means y poor contact conditions between sald contacts and the rail.

5. A rail flaw detector comprising a plurality of spaced brushes adapted to be moved along the rail, means for supplying electric current thereto, a pair of contacts between said brushes, means oppositely responsive to variations in the voltage-drop due to tiaws in the rail and those due to loss of electrical contact with said rail by said contacts, said ylast-named means com rising opposed potenpotentiometera being tiomters one of sai connected to said contacts, the other of sai potentiometers being connected to "a source of E. M. F. of known stren h, means for amplifying the differential o said potentiometers, indicating means, and means whereby said'indicating means is actuated in one direction or the other according as said di rential is ater or less than a predetermin normal di erential.

A rail flaw detector. comprising a plu-l rality of spaced brushes adapted to-be moved along the rail, means for supplyingheavy current thereto, a pair of contacts tween said brushes, means responsive to variations in voltage drop between said contacts dueto flaws inthe rail, means ve to 'greater variations in voltagedro due to rail joints, indicating-.means adap to be actuated by. said firsty responsive means, and means whereby said indicating means is rendered ineectlve when said second responsive means is' rendered efectivo.

7. A rail flaw Adetector lcomprising a plurality of spaced brushes adapted to be moved along the rail, means for supplying heavy current thereto, a pair` of contacts between said brushes, means responsive to variations in volt drop between said contacts due to aws 1n the rail means responsive to greater, variations in voltage drop due to ,'a'il join indicating means, means including electri y IIB lll

points, detector means also movable with said first means and responsive to variations in the characteristics of currentiiow, and rail marking means actuated therefrom to place a mark on the rail adjacent each flaw.

In testimony whereof have afxed my sig-l nature.

HARCGURT C. DRAKE. 

